DAY 2 DISCUSSION - 01-05-07

[Paul Sherman]

Looking good for Tomorrow for the guys to hopefully see there first Supercell and there is a good Tornado risk as these storms should be moving at a snails pace.

From SPC

...CENTRAL TX...

WHILE MID LEVEL FLOW WILL BE 30KT OR LESS ACROSS CENTRAL TX...THE

VEERING PROFILES WITH 40KT OF SFC-6KM SHEAR WILL SUPPORT BOTH

MULTICELL AND ISOLATED SUPERCELL ACTIVITY. WITH SLY BOUNDARY LAYER

WINDS CONTINUING TO FEED NEAR 70F DEW POINTS INTO CENTRAL

TX...AFTERNOON MLCAPES WILL LOCALLY RISE TO ABOVE 2000 J/KG.

THUNDERSTORMS WILL DEVELOP WITH AFTERNOON HEATING MUCH OF CENTRAL

TX...HOWEVER THE EVOLUTION OF DY1 CONVECTION AND DEVELOPMENT OF

OUTFLOW BOUNDARIES WILL MODULATE THE MORE FAVORED AREAS OF SURFACE

BASED INITIATION ON TUE.

SUFFICIENT SHEAR GIVEN THE INSTABILITY FOR SUPERCELLS TO FORM.

PRIMARY THREAT WILL BE LARGE HAIL WITH RATHER SLOW STORM

MOTION...HOWEVER ISOLATED TORNADOES ARE ALSO POSSIBLE.

..HALES.. 04/30/2007

Paul Sherman

[BrickFielder]

Yes I think Texas is probably the place to be on Tuesday.

Less upper level support on Wednesday but stability is pretty much limited to Texas. I think I would head out west a bit where an area of upper level vorticity moves in.

[NL]

DAY 1 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

1241 AM CDT TUE MAY 01 2007

VALID 011200Z - 021200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF SRN PLAINS...

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE NRN OH

VALLEY...

...SRN PLAINS...

A WELL-DEFINED UPPER-LEVEL LOW EVIDENT ON WATER VAPOR IMAGERY OVER

THE TX PANHANDLE WILL MOVE SLOWLY EWD ACROSS OK TODAY AND TONIGHT.

LARGE-SCALE ASCENT ASSOCIATED WITH THE UPPER-LEVEL LOW WILL SHIFT

EWD INTO CNTRL TX THIS AFTERNOON AND AWAY FROM THE AXIS OF STRONGEST

INSTABILITY. ALTHOUGH SOME THUNDERSTORM ACTIVITY SHOULD BE ONGOING

THIS MORNING ACROSS NORTH AND CNTRL TX...THUNDERSTORM COVERAGE

SHOULD INCREASE THIS AFTERNOON AS DESTABILIZATION TAKES PLACE ACROSS

THE REGION. MCS DEVELOPMENT APPEARS LIKELY ACROSS PARTS OF CNTRL AND

NORTH TX THIS EVENING WITH STORMS MOVING SLOWLY EWD DURING THE

OVERNIGHT PERIOD.

FORECAST SOUNDINGS ACROSS CNTRL AND NORTH TX LATE THIS AFTERNOON

SHOW VEERING WIND PROFILES WITH HEIGHT RESULTING IN 0-6 KM SHEAR

VALUES IN THE 35 TO 45 KT RANGE. THIS SHOULD BE SUFFICIENT FOR

SUPERCELLS ESPECIALLY NEAR LOCALLY MAXIMIZED INSTABILITY.

HOWEVER...A MIX OF ORGANIZED MULTICELLS AND BOWING LINE-SEGMENTS

WILL ALSO BE LIKELY DUE TO THE LARGE NUMBER OF STORMS. SUPERCELLS

WITH LARGE HAIL POTENTIAL SHOULD BE MOST NUMEROUS ALONG THE I-35

CORRIDOR IN CNTRL TX WHERE INSTABILITY AND SHEAR PARAMETERS ARE

FORECAST TO BE BETTER PHASED. BACKED SFC WINDS AND A WELL-DEFINED

LOW-LEVEL JET SHOULD RESULT IN FAVORABLE LOW-LEVEL SHEAR PROFILES

FOR A TORNADO THREAT. THE GREATEST TORNADO THREAT SHOULD EXIST WEST

OF THE LOW-LEVEL JET WITH SUPERCELLS IN CNTRL TX AND NORTH TX LATE

THIS AFTERNOON AND EARLY THIS EVENING.

[NL]

The team are'nt to far away from the anticipated area for storms today, as Bricky has already

pointed out. With the storms progged to move slowly chasing should be a doddle today.

[pottyprof]

Some very high CAPE levels showing on GFS for 18z -21z in that area NL. Could be that they are spot on for a good chase day.

[NL]

Certainly does Potty, looking forward to the chase today..

[Paul Sherman]

Hi Guys, Just awoken and its 720am here, had our first MCS Of the Tour last night, a strike very close to the Hotel at 1am sounded like a bomb going off, then a more organised Storm moved over at 3am giving us a nice Lightning show for the guys, unfortunately the rain was torrential so could not get any shots and just took refuge in the Hotel. Today is looking very good for Photo for you all.

Report back later. Going to head just South of I20 for our target but will firm up on loacation when Nick gets up.

Paul Sherman

[Roger J Smith]

Just looking at the radar now, two trailing clusters near Brownwood and Abilene look like they might give a good chase scenario, for one thing they may be easier to view than the larger rain-shrouded cluster further east.

Of these two, the second one near Abilene might tend to increase in intensity while the other one may lose intensity during the day. Might be tricky navigating through some stormy conditions to be in place for this trailing cell, but sky conditions in general with the drier air moving in from the west could give the best video opportunities.

Texas state report mentions severe flooding in Brownwood overnight and some roads closed in that area.

Good luck with your chase, I'm chasing the almighty dollar myself.

[kold weather]

Hi Roger, am watching those cells myself right now, they do look very potent right now and are returning some decent ehcoes as well. Sat. suggests as you say Roger the cells in the foward part of the line do look rather cloud covered at the moment, but the two trailing cells, esp the one to the NW looks very neat, if you want good photo chances best to try and approach it from the NW side if possible. From the looks of things the cells are firing up and developing in a line with new cells forming on the SE side of the parent anvil. Cloud tops are at the present around 40,000 feet accoring to radar.

If i was out there I'd try to keep near the eastern side of those trailing cells, esp as I'd expect some more cells to go up near that line as the afternoon carries on. The air out ther eis quite dry relative to that on the frontal system, though even then humdity is progged to be up to around 55-65% at lower levels such as 850hpa and the 12z obs showed 86% humidty in N.Texas at 12z, tohugh given the fronts position at the time no doubt the drier air is feeding in and lowering that. Higher up and the air is a little less moist however if the low level moisture does increase like the GFS progs then low level cloud could become a annoying issue in the eveing hours. Convection just behind the line of storms present should have no trouble in developing, obs from the atmopshere suggest that the convective tmep is only around 24C and the maxes are progged in the zone to be around 28C according to the 12z obs, tohugh witha drier atmopshere pushing in the temps may wlel peak a little higher then that locally and also given the temps and dew-points profiles ther eis a lot of cape indeed, the models progs about 1000-2000 arounsd that trailing edge, the only shame is that the cape is even higher to the west, upto 3000kjs but with no trigger, shame!

As for severe weather, probably moderate chance of fairly sizeable hail and some very heavy rain possible given there is still pretty hefty cape there to use and there is progged to be 1.57 inches of Precipitable water. There is really no upper support at all however in terms of jet so any severe weather should be limited to that I suspect, because the shear is rather weak at all levels, though as suggested there is a shot at some weak supercells to form because the directional shear is better with a real veer present because of the way the low is stacked into the atmopshere at a slight angle so slowly rotating supercells possibly but nor as severe as what they could be. Storm motion behind the front is about 325-335 at 15knts and along the front or to the east 250 at 18-20kts.

Good luck guys, i'll be rooting for you all!

Edited May 1, 2007 by kold weather

[pottyprof]

The team are currently heading south along the 183 towards Brownwood, along the back edge of the storms.

[Louby]

fingers crossed for you guys! Wish I was out there with you!

definatley looking good for you today! good luck :o

[pottyprof]

The team are currently heading south on the 281, going to pass just to the east of Brownwood, skies rapidly clearing and should get initiation in the next 2 hours, so if a Supercell fires they will be in Chase mode in the next 3-4 hours.

Nice bit of wind convergence over central TX on the latest GFS run..

[Greyowl]

Things are looking good for you lucky people today. Good hunting guys.

[pottyprof]

Looking like a supe heading towards San Saba..

Those storms to the east have woken up again. Look at that streamer WNW of Bryan.

[NL]

M'd issued potential tornado threat.

MESOSCALE DISCUSSION 0638 NWS STORM PREDICTION CENTER NORMAN OK 0331 PM CDT TUE MAY 01 2007 AREAS AFFECTED...SOUTH CENTRAL TEXAS CONCERNING...SEVERE POTENTIAL...TORNADO WATCH LIKELY VALID 012031Z - 012200Z SEVERE THUNDERSTORMS CAPABLE OF PRODUCING TORNADOES...STRONG WINDS...AND LARGE HAIL WILL BE POSSIBLE THIS LATE AFTERNOON AND EVENING ACROSS SOUTH CENTRAL TEXAS. A TORNADO WATCH WILL BE ISSUED FOR THIS REGION SHORTLY. LATEST 20Z SURFACE ANALYSIS INDICATES A WEAK OUTFLOW/CONVERGENCE BOUNDARY ROUGHLY FROM SAN ANGELO SOUTHEASTWARD TO NEAR HOUSTON...AND THE ATMOSPHERE CONTINUES TO DESTABILIZE IN THIS REGION INTO A VERY UNSTABLE ENVIRONMENT WITH MUCAPE VALUES FROM 2500 TO 3500 J/KG AS SURFACE HEATING CONTINUES. VISIBLE SATELLITE IMAGERY SHOWS A TREND TOWARDS SURFACE BASED CONVECTIVE DEVELOPMENT AS THE WEAK CAP AND MID-LEVEL CLOUD LAYER ERODES OVER THE REGION...CURRENT RADAR IMAGERY ALSO CONFIRMS THIS WITH A DEVELOPING STORM OVER MCCULLOCH COUNTY. VERTICAL SHEAR PROFILES ARE FAVORABLE FOR ROTATING STORMS. ACROSS THE AREA...18Z RUC POINT FORECAST SOUNDINGS VALID AT 20Z SHOW SFC TO 3KM HELICITY VALUES AROUND 150-250 M2/S2. STORMS ARE EXPECTED TO FORM ALONG THE CONVERGENCE BOUNDARY OVER THE NEXT SEVERAL HOURS AND MOVE EAST-SOUTHEASTWARD. GIVEN THE THERMODYNAMIC AND VERTICAL SHEAR ENVIRONMENT...SUPERCELL STORMS ARE POSSIBLE WITH TORNADOES.

[pottyprof]

I think the powder keg is nearly full NL.. wonder when the touch paper gets lit?? :o

Tornado warning now on that supercell near san saba

[NL]

Hopefully soon potty, initiation has been/is really slow today, but great things arise to those who wait!!

Could be quite an explosive night in Texas..

[pottyprof]

Aye NL.. could be brown trouser time for Nick.. :o

[NL]

Yeah hope Paul catches him on video, Really good call the team has made today, gonna be right on that cell.

[pottyprof]

BULLETIN - EAS ACTIVATION REQUESTED

TORNADO WARNING

NATIONAL WEATHER SERVICE SAN ANGELO TX

356 PM CDT TUE MAY 1 2007

THE NATIONAL WEATHER SERVICE IN SAN ANGELO HAS ISSUED A

* TORNADO WARNING FOR...

EAST CENTRAL MCCULLOCH COUNTY IN WEST CENTRAL TEXAS...

WEST CENTRAL SAN SABA COUNTY IN WEST CENTRAL TEXAS...

* UNTIL 445 PM CDT

* AT 352 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A

SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO 2 MILES

NORTHEAST OF ROCHELLE...OR ABOUT 12 MILES NORTHEAST OF BRADY...

MOVING SOUTHEAST AT 10 MPH.

* THE TORNADO IS EXPECTED TO BE NEAR...

US-190 NEAR THE MCCULLOCH-SAN SABA COUNTY LINE BY 420 PM CDT...

HALL BY 425 PM CDT...

RICHLAND SPRINGS BY 445 PM CDT...

THE SAFEST PLACE TO BE DURING A TORNADO IS IN A BASEMENT. IF NO

BASEMENT IS AVAILABLE...SEEK SHELTER ON THE LOWEST FLOOR OF THE

BUILDING IN AN INTERIOR HALLWAY OR ROOM SUCH AS A CLOSET. IF IN

MOBILE HOMES OR VEHICLES...EVACUATE THEM AND GET INSIDE A SUBSTANTIAL

SHELTER.

IN ADDITION TO THE TORNADO...THIS STORM IS CAPABLE OF PRODUCING HEN

EGG SIZE HAIL AND DESTRUCTIVE STRAIGHT LINE WINDS.

A TORNADO WATCH REMAINS IN EFFECT UNTIL 1100 PM CDT TUESDAY EVENING

FOR WEST CENTRAL TEXAS.

Nice sat pic of it sat in the middle..

[pottyprof]

Just noticed that.... HEN EGG HAIL.... LMAO!!! ooo err

[Gorky]

Hello, the team are currently sat in Lampassa Texas, about 30 miles east of the tornado warned cell. We are going to let it cross the river before chasing it as road options across are pretty sparse It's not the best chase country around here but it's moving slowly so hopefully that will help. Expect more updates later!

[NL]

Just noticed that.... HEN EGG HAIL.... LMAO!!! ooo err

Ha Ha, cracking stuff!! never heard hail being called hen egg size before!!

[pottyprof]

Nice one Nathan.. thanks for the update.. Stay safe everyone..

Ha Ha, cracking stuff!! never heard hail being called hen egg size before!!

It's probably chuckieing it down....

[NL]

That cell is now reaching a staggering 48000ft...!!!